Andromeda III

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Andromeda III
Observation data (J2000 epoch)
Constellation Andromeda
Right ascension 00h 35m 33.8s [1]
Declination +36° 29 52 [1]
Redshift −351±9 km/s [1]
Distance 2.44 ± 0.08  Mly (748 ± 25  kpc) [2]
Apparent magnitude  (V)15.0 [1]
Characteristics
Type dSph [1]
Apparent size  (V)4.5 × 3.0 [1]
Notable features satellite galaxy of M31
Other designations
AndIII, [1] RC2 Anon 0032+36, [1] PGC 2121 [1]

Andromeda III is a dwarf spheroidal galaxy about 2.44 million light-years away in the constellation Andromeda. It is part of the Local Group and is a satellite galaxy of the Andromeda Galaxy (M31). The galaxy was discovered by Sidney van den Bergh [2] on photographic plates taken in 1970 and 1971. [3]

Contents

Observations of the dwarf galaxy using the WFPC2 in 2002 indicate that the bulk of the galaxy is around three billion years younger than the general population of globular clusters in our own galaxy. However, there are some older stars that are comparable in age to the Milky Way galactic clusters. There is no evidence for younger stars in this dwarf galaxy, suggesting no star formation is occurring. The dwarf galaxy is located at a distance of around 75  kpc from the center of M31. [4] A total of 56 variable stars have been discovered in And III, including 51 RR Lyrae variables. [5]

See also

Related Research Articles

<span class="mw-page-title-main">Globular cluster</span> Spherical collection of stars

A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".

<span class="mw-page-title-main">Local Group</span> Group of galaxies that includes the Milky Way

The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10^6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.

<span class="mw-page-title-main">Andromeda Galaxy</span> Barred spiral galaxy in the Local Group

The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a D25 isophotal diameter of about 46.56 kiloparsecs (152,000 light-years) and is approximately 765 kpc (2.5 million light-years) from Earth. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.

<span class="mw-page-title-main">Triangulum Galaxy</span> Spiral galaxy in the constellation Triangulum

The Triangulum Galaxy is a spiral galaxy 2.73 million light-years (ly) from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC (New General Catalogue) 598. With the D25 isophotal diameter of 18.74 kiloparsecs (61,100 light-years), the Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Andromeda Galaxy and the Milky Way.

<span class="mw-page-title-main">Pegasus Dwarf Spheroidal Galaxy</span> Dwarf spheroidal galaxy in the constellation Pegasus

The Pegasus Dwarf Spheroidal is a dwarf spheroidal galaxy about 2.7 million light-years away in the constellation Pegasus. The Pegasus Dwarf is a member of the Local Group and a satellite galaxy of the Andromeda Galaxy (M31).

<span class="mw-page-title-main">Pegasus Dwarf Irregular Galaxy</span> Dwarf irregular galaxy in the constellation of Pegasus

The Pegasus Dwarf Irregular Galaxy is a dwarf irregular galaxy in the direction of the constellation Pegasus. It was discovered by A. G. Wilson in the 1950s. The Pegasus Dwarf is a companion of the Andromeda Galaxy in the Local Group.

<span class="mw-page-title-main">Messier 32</span> Dwarf elliptical galaxy in the constellation Andromeda

Messier 32 is a dwarf "early-type" galaxy about 2,650,000 light-years (810,000 pc) from the Solar System, appearing in the constellation Andromeda. M32 is a satellite galaxy of the Andromeda Galaxy (M31) and was discovered by Guillaume Le Gentil in 1749.

<span class="mw-page-title-main">Dwarf galaxy</span> Small galaxy composed of up to several billion stars

A dwarf galaxy is a small galaxy composed of about 1000 up to several billion stars, as compared to the Milky Way's 200–400 billion stars. The Large Magellanic Cloud, which closely orbits the Milky Way and contains over 30 billion stars, is sometimes classified as a dwarf galaxy; others consider it a full-fledged galaxy. Dwarf galaxies' formation and activity are thought to be heavily influenced by interactions with larger galaxies. Astronomers identify numerous types of dwarf galaxies, based on their shape and composition.

<span class="mw-page-title-main">Messier 110</span> Satellite galaxy of the Andromeda Galaxy

Messier 110, or M110, also known as NGC 205, is a dwarf elliptical galaxy that is a satellite of the Andromeda Galaxy in the Local Group.

<span class="mw-page-title-main">NGC 185</span> Galaxy in the constellation Cassiopeia

NGC 185 is a dwarf spheroidal galaxy located 2.08 million light-years from Earth, appearing in the constellation Cassiopeia. It is a member of the Local Group, and is a satellite of the Andromeda Galaxy (M31).

<span class="mw-page-title-main">Dwarf spheroidal galaxy</span> Low-luminosity galaxy of old stars & little dust

A dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population. They are found in the Local Group as companions to the Milky Way and as systems that are companions to the Andromeda Galaxy (M31). While similar to dwarf elliptical galaxies in appearance and properties such as little to no gas or dust or recent star formation, they are approximately spheroidal in shape and generally have lower luminosity.

<span class="mw-page-title-main">Andromeda I</span> Dwarf galaxy in the constellation Andromeda

Andromeda I is a dwarf spheroidal galaxy (dSph) about 2.40 million light-years away in the constellation Andromeda. Andromeda I is part of the local group of galaxies and a satellite galaxy of the Andromeda Galaxy (M31). It is roughly 3.5 degrees south and slightly east of M31. As of 2005, it is the closest known dSph companion to M31 at an estimated projected distance of ~40 kpc or ~150,000 light-years.

<span class="mw-page-title-main">Tucana Dwarf</span> Dwarf galaxy in the constellation Tucana

The Tucana Dwarf Galaxy is a dwarf galaxy in the constellation Tucana. It was discovered in 1990 by R.J. Lavery of Mount Stromlo Observatory. It is composed of very old stars and is very isolated from other galaxies. Its location on the opposite side of the Milky Way from other Local Group galaxies makes it an important object for study.

<span class="mw-page-title-main">Ursa Minor Dwarf</span> Dwarf spheroidal galaxy

The Ursa Minor Dwarf is a dwarf spheroidal galaxy, discovered by A.G. Wilson of the Lowell Observatory, in the United States, during the Palomar Sky Survey in 1955. It appears in the Ursa Minor constellation, and is a satellite galaxy of the Milky Way. The galaxy consists mainly of older stars and seems to house little to no ongoing star formation. Its centre is around 225,000 light years distant from Earth.

<span class="mw-page-title-main">Fornax Dwarf</span> Dwarf galaxy in the constellation Fornax

The Fornax Dwarf Spheroidal is a dwarf elliptical galaxy in the constellation Fornax that was discovered in 1938 by Harlow Shapley. He discovered it while he was in South Africa on photographic plates taken by the 24 inch (61 cm) Bruce refractor at Boyden Observatory, shortly after he discovered the Sculptor Dwarf Galaxy.

<span class="mw-page-title-main">Andromeda II</span> Dwarf spheroidal galaxy in the constellation Andromeda

Andromeda II is a dwarf spheroidal galaxy about 2.22 Mly away in the constellation Pisces. While part of the Local Group, it is not quite clear if it is a satellite of the Andromeda Galaxy or the Triangulum Galaxy.

Andromeda V is a dwarf spheroidal galaxy about 2.52 Mly away in the constellation Andromeda.

<span class="mw-page-title-main">Cassiopeia Dwarf</span> Galaxy in the constellation Cassiopeia

The Cassiopeia Dwarf (also known as Andromeda VII) is a dwarf spheroidal galaxy about 2.45 Mly away in the constellation Cassiopeia. The Cassiopeia Dwarf is part of the Local Group and a satellite galaxy of the Andromeda Galaxy (M31). In the sky, it appears behind the Milky Way's galactic plane, and so it is reddened by 0.194 magnitudes. With a luminosity of 1.8×107 L and a stellar mass of 19.73×106 M, it is the brightest and most massive of the Andromeda Galaxy's dwarf spheroidal galaxy satellites. It also has the highest metallicity out of all of them.

References

  1. 1 2 3 4 5 6 7 8 9 "NASA/IPAC Extragalactic Database". Results for AndIII. Retrieved 2006-12-18.
  2. 1 2 McConnachie, A. W.; et al. (2005). "Distances and metallicities for 17 Local Group galaxies". Monthly Notices of the Royal Astronomical Society . 356 (4): 979–997. arXiv: astro-ph/0410489 . Bibcode:2005MNRAS.356..979M. doi: 10.1111/j.1365-2966.2004.08514.x .
  3. van den Bergh, Sydney (January 1972). "Search for Faint Companions to M31". Astrophysical Journal. 171: L31. Bibcode:1972ApJ...171L..31V. doi: 10.1086/180861 .
  4. Da Costa, G. S.; et al. (July 2002). "The Dwarf Spheroidal Companions to M31: WFPC2 Observations of Andromeda III". The Astronomical Journal. 124 (1): 332–348. arXiv: astro-ph/0204109 . Bibcode:2002AJ....124..332D. doi:10.1086/340965. S2CID   12713887.
  5. Pritzl, Barton J.; et al. (May 2005). "The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda I and Andromeda III". The Astronomical Journal. 129 (5): 2232–2256. arXiv: astro-ph/0501083 . Bibcode:2005AJ....129.2232P. doi:10.1086/428372. S2CID   9749493.